大般涅槃經義記 7.223

7.223

第二門中，業淨列名，次辯其相。「凡業不淨」舉穢顯淨，「佛業清淨」彰淨異穢，「以大淨」下將義顯體，成涅槃大。

In the second section, purity of action is listed by name, and next its characteristics are discriminated. "The actions of ordinary people are impure" adduces defilement to reveal purity. "The actions of the Buddha are pure" displays that purity is distinct from defilement. From "Because of great purity..." onward, meaning is taken up to reveal the essence, establishing the greatness of nirvāṇa.